Internal combustion engine-electric power unit



C. SCHAER Sept. 22, 1936.

INTERNAL COMBUSTION ENGINE-ELECTRIC POWER UNIT Filed March 17, 1933INJENTU R 6 KW J/QZW BY I ATI'D RN Eh/ Patented Sept. 22, 1936 srsresINTERNAL COMBUSTION ENGINE-ELECTRIC POWER UNIT Charles Sehaer,Langenthal, Switzerland, assignor to firm Sulzer Freres Societe Anonyme,Winterthur, Switzerland Application March 17, 1933, Serial No. 661,238In Switzerland March 24, 1932 Claims.

This invention relates to internal combustion engine-electric powerplants particularly, though not exclusively, for the propulsion ofvehicles.

An internal combustion engine-electric power 5 plant according to theinvention comprises a control generator driven by the engine, andcontrol apparatus actuated in accordance with the output voltage of thecontrol generator so as to control the excitation current of the maincurrent generator. In this way the speed of the engine will bemaintained constant at the value desired in spite of load variations.

The control apparatus may comprise a relay or relays actuated inaccordance with the output voltage of the control generator and meanscontrolled by the relay so as to regulate the excitation current of themain generator. Alternatively the control apparatus may comprise anelectric motor having two opposed windings one of which is energized bycurrent derived from the control generator and the other by currentderived from a constant voltage source, and means operated by the motorto control the excitation current of the main generator.

In the accompanying drawing-- Figure 1 illustrates diagrammatically andby way of example one construction according to the invention,

Figures 2 and 3 show respectively two modifications of the controlapparatus illustrated in Figure 1 and Figure 4 illustrates anotherconstruction also according to the invention.

Figure 5 illustrates still another construction according to theinvention.

In the construction illustrated in Figure 1 the power plant comprises aninternal combustion engine I which drives a main current generator 2 theexcitation circuit 3 of which is energized either in shunt or from aseparate source. A

control generator 4, also driven by the engine I has an excitationcircuit 5 energized from a battery 8, the control generator 4 supplyinga circuit 1 containing two relays 8 and 9 and a resistance ill variableby means of a contact arm I l. Each of the relays 8 and 9 controls twopairs of contacts, one pair associated with a circuit [2 and the otherpair with a circuit l3, the circuit l2 including a solenoid [4 Whilstthe circuit ill includes a solenoid Hi. The solenoids l4 and I5 actuate,as hereinafter described, a piston valve It so as to control a piston llby regulating the supply of pressure medium to a cylinder l8 withinwhich the piston IT can reciprocate. The piston 55 valve I6 is normallyheld in its central position as shown by centering springs l9. Thepiston I1 is operatively connected by a rod 20 to a pivoted contact arm2! of a rheostat 22 whereby the excitation current flowing through thefield winding 3 of the main current generator 2 can be regulated.

The engine I is furnished with a centrifugal governor 23 whereby thefuel supplied to the engine is regulated in accordance with the loadthereon, the tension of the loading spring or is springs of the governor23 being adjustable by means of the arm ll acting through a rod 24,bellcrank lever 25 and plunger 26.

The relays 8 and 9 are such that the armature of the relay 8 will beraised only when the output 15 voltage of the control generator 4exceeds a predetermined normal value, whilst the armature of the relay 9will be raised when the output voltage of the control generator hasreached a value somewhat below the said normal. 20

With the parts in the positions shown in Figure 1 the output voltage ofthe control generator 4 is substantially normal, the relay 9 being inits raised position and the relay 8 in its lower position. If now thespeed of the engine increases, 25 due for example to a decrease in theload on the main generator 2, the output voltage of the controlgenerator 4 will increase to a value above normal whereby the armatureof the relay 8 will be raised, 1'. e. to the position corresponding to30 that of the relay 9. The circuit l2 will in this way be closed sothat the solenoid l 4 will move the piston valve I 6 to the right asviewed in Figure 1 and pressure medium will be delivered to the cylinderl8 so as to move the piston I! to the left. In 5 this way the resistance22 will be decreased and the excitation current through the fieldwinding 3 increased, the load on the engine and therefore the speed ofthe engine and of the control generator 4 being thereby restored tonormal. The 40 output voltage of the control generator 4 is in this wayrestored to normal and the relay 8 will return to the position shown sothat the solenoid l 4 will be deenergized and the piston valve l6returned under the action of its control springs l9 to its 45 centralposition shown in the drawing. The parts are then in their normalpositions shown in Figure 1.

If now the speed of the engine decreases due, for example, to anincrease in the load on the main generator 2, the output voltage of thecontrol generator 4 will decrease to such a value below normal that thearmature of the relay 9 Will descend to the position corresponding tothat of the relay 8 whereby the solenoid l5 will be energized and thepiston valve EB moved to the left as viewed in Figure 1. Pressure mediumwill thus be admitted to the cylinder 53 on the left or the piston llwhich will thereupon be moved to the right so as to increase theresistance 22 and decrease the excitation current flowing through thefield winding 3. The load on the engine will thus be decreased so thatthe engine speed and the speed of the control generator will be restoredto the normal value. The armature of the relay g will then return to theposition shown in Figure 1 and the solenoid it will thus be deenergizedso that the piston valve it will return to its normal or centralposition.

Arrangement of the relays 8 and 9 so as to be operated at voltages ofthe control generator respectively above and below normal voltage, withV a constant resistance in the circuit l and constant excitation currentflowing through the winding 5 as above described, will result in thenormal voltage of the control generator l being produced atpredetermined torque and engine speed. The unit may however be adjustedfor any given torque between full load and idle running by moving thelever ll so as to adjust the value of the resistance to whereupon adifferent engine speed will be required to produce the normal outputvoltage from the control generator 6, the tension of the governorloading spring being simultaneously adjusted through the rod 2 3 andbell crank lever 25. When the engine is not furnished with a governorand the fuel supply is manually regulated the speed of the engine for agiven normal output voltage of the control generator t may be adjustedby varying the resistance it.

The circuits l2 and is may, if desired, be controlled by vibrationregulators, or the like. Further instead of employing two relays asabove described a single relay El (Figure 2) may be employed. The relay2? is such that with the normal outputvoltage from the control generatori the armature of the relay 2? will be in the central positionrshownwhilst, with the output voltage of the control generator 5 at a valueabove or below normal the said armature will be in the raised or loweredposition respectively so as to energize the circuit E2 or 53.

As shown in Fig. 3, the piston valve l6 may be actuated by two opposedcoils 23, 28 both arranged to influence an armature 3G operativelyconnected to one end of the piston valve 56. The coil 28 is connectedacross the control generator l whilst the opposed coil 29 is connectedacross the battery 5. Thus, while the voltage of the circuit 7 is equalto that of the battery 6 the piston valve it will remain in its centralposition shown in the drawing thereby cutting off the supply of pressuremedium to the cylinder l8. When the voltage of the circuit 7 exceedsthat of the battery 6 however the influence of the coil 28 on thearmature (it will predominate and the piston valve it will be moved tothe right as viewed in Figure 3 so that the piston i? will be moved tothe left and the resistance 22 decreased. Conversely, when the voltageof the circuit l falls below that of the battery 6 the influence of thecoil 29 on the armature 39 will predominate and the piston ill will bemoved to the right so as to increase the resistance 22 and decrease thecurrent flowing through the field winding 3. In either case the enginespeed necessary to produce the desired normal output voltage from thecontrol generator l will 'be restored by the adjustment of the fieldcurrent flowing through the field winding 3 so that the normal outputvoltage of the control generator 4 will be restored and the piston valve56 returned to its central position.

In the construction illustrated in Figure 4 control of the resistance 22is eiiected by means of an electric motor generally indicated at 3! andcomprising a winding 32 connected across the control generator i and anopposed winding 33 connected across the battery 6. When the voltageacross the winding 32 exceeds that across the opposed Winding 33 thearmature 35 of the motor 3! will be rotated in one direction therebytransmitting movement through a gear 36 to the contact arm M of theresistance 22 which will thus be, in effect, decreased. Conversely, whenthe voltage across the winding 33 exceeds that across the opposedwinding 32 the armature 35 will be rotated in the opposite direction toefiect an increase of the resistance 22. A variable resistance Si in thefield circuit of the control generator can be adjusted so as, in effect,to vary'the engine speed which is to be maintained. Instead of providingthe opposed field windings 32 and 33 of Fig. 4, opposed armaturewindings may be used as shown in Fig. 5 at 32st on armature 35a and at330, on armature 3517.

W ith a view to limiting the range of regulation or? the resistance 22,for example during starting of the power unit, means may be providedwhich, when operated by the driver, causes the contact arm 2i or themotor 31 to be locked in position. To this end a coil 43 may beenergized through a circuit 6G fromthe drivers cabin, the coil 43 whenenergized holding a latch 3E out of the path of a nose l2 provided onthe transmission mechanism 36. When during starting, the coil 43 isdeenergized the latch Lil will fall by gravity so as to lie in the pathof the nose i2 whereupon the contact arm M which, when the unit isinoperative will occupy the position at which the value of theresistance 22 is a maximum, cannot be moved beyond the positionindicated at I. The value of the resistance 22 cannot therefore bedecreased below a predetermined value until the driver raises the latchll by energizing the coil 53. In this way the possibility of anexcessive flow of current through the field winding 3 of the maingenerator 2 during starting of the unit is precluded.

Instead of locking the contact lever 21 in this manner an additionalresistance actuated from the drivers cab may be switched into theexcitation circuit 3 of the main current generator 2, so that the drivermay control the maximum speed to which the vehicle automatically adjustsitself.

It will therefore be seen that in a power plant according to theinvention the speed of the internal combustion engine will be maintainedsubstantially constant in spite of variations in the load thereon.

It will be understood that the constructions above described are givenby way of example only and that details may be modified. Thus, forexample, instead'of employing relays such as those illustrated inFiguresl or 2 any other suitable form of relay such, for example, as that ofthe polarized or, electron type may be employed. The means for actuatingthe contact arm of the rheostat associated with the field winding of themain generator may be operated by hydraulic or pneumatic means and,instead of employing a piston valve for regulating the supply ofpressure medium to the piston operatively connected to the rheostatvalves, for example of the poppet type, may be employed. Further, ifdesired, ad- I5 justment of the resistance in circuit with the fieldwinding of the main generator may be effected by means of an electricmotor. Instead of employing a centrifugal governor as above describedthe fuel supply may be regulated manually and a safety regulatorprovided.

I claim:

1. In an engine-electric power set, an internal combustion engine, amain electric generator driven by said engine and having an excitationcircuit, a device operated by a pressure medium for adjusting theresistance of said circuit, a control generator driven by said engine,and control means for controlling said device comprising a valve forcontrolling the flow of pressure medium to said device, and twoelectromagnetic relays responsive to different voltages of said controlgenerator, said relays actuating said valve to thereby cause theresistance for regulating the current of said main generator to beadjusted.

2. In an engine-electric power set, an internal combustion engine, amain electric generator driven by said engine and having an excitationcircuit, a variable resistance in said excitation circuit forcontrolling the excitation current, a control generator driven by saidengine, and control means responsive to variations in the output voltageof said control generator, but operable only after said variations havereached a predetermined amount, said control means controlling theoperation of a power-operated device, said power-operated device beingoperable to vary said resistance.

3. A set according to claim 2, in which said power operated device has avalve for controlling said device, and control relays are provided forcooperating with said valve for varying the torque and the speed of saidengine.

4. In an engine-electric power set, an internal combustion engine, amain electric generator driven by said engine and having an excitationcircuit, a variable resistance in said excitation circuit forcontrolling the excitation current, a control generator driven by saidengine, and control means responsive to variations in the output voltageof said control generator, but operable only after said variations havereached a predetermined amount, said control means controlling theoperation of a power-operated device, said power-operated device beingoperable to vary said resistance, said control means in controlling theworking of the power-operated device causing a subsequent and furthervariation of the value of said resistance only when the output voltageof said control generator differs from its predetermined value by anamount substantially equal to that which originally caused the operationof said control means.

5. In an engine-electric power set, an internal combustion engine, amain electric generator driven by said engine and having an excitationcircuit, means for controlling the excitation circuit, a controlgenerator driven by said engine, means for regulating the speed of theengine to give a desired normal output voltage of the control generator,and control means responsive to variations in the output voltage of saidcontrol generator, but operable only after said variations have reacheda predetermined amount, means operable by said control means for varyingthe resistance in said excitation circuit, and said control means beingoperable to adjust the resistance in said excitation circuit until afterthe output voltage of said control generator has again reachedsubstantially its normal value.

CHARLES SCHAER.

